The Best Coconut Cake Ever!

Prepare cake mix according to the directions on the box. Bake in two 9-inch round pans. Cool, slice through middle, making four thin layers. Combine sugar, sour cream and coconut. Mix well, set aside 1 cup. Spread coconut mixture between layers; then mix the 1 cup of mixture with the cool whip and spread on sides and top. Keep refrigerated or frozen until ready to eat.